A major project of this section is the development of newstatistical genetics methodology as prompted by the needs of ourapplied studies. This year Dr. Bailey-Wilson developed severalnew methods. The first, in collaboration with Dr. Gloria Ho, isan extension of the Transmission Disequilibrium Test (TDT) andthe Sibling-Transmission Disequilibrium Test (S-TDT) and thecombined test (C-TDT) to traits that are caused, in whole or inpart, by loci on the X chromosome. This work is in press in theAmerican Journal of Human Genetics. The second project, incollaboration with Dr. Silvano Presciuttina who is on sabbaticalat IDRB from the University of Pisa, is the development of astepwise procedure for using a few genetic markers at each stepto try to differentiate siblings from unrelated individuals. Thismethodology has applications in linkage analysis and inforensics. A manuscript has been submitted for publication. Thethird project, in collaboration with Dr. Jim Malley at CIT, NIH, is the development of a new method for family based associationtests that appears considerably more powerful than the TDT butmore robust to false positives than is case-control association.These projects are ongoing. - statistical genetics methodology, theory, X-linked TDT, stepwise relationship determination